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Topics /
Systems & Performance
The most popular blog posts about systems & performance on Hacker News. 4,390 posts.
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Two interesting XOR circuits inside the Intel 386 processor
Intel's 386 processor (1985) was an important advance in the x86 architecture, not only moving to a 32-bit processor but also switching to a...
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The .NET IL Interpreter
Whilst writing a previous blog post I stumbled across the .NET Interpreter, tucked away in the source code. Although, it I’d made even the smallest amount of effort to look for it, I’d have easily found it via the GitHub ‘magic’ file search:
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IPv4, IPv6, and a sudden change in attitude
A few years ago I wrote [_The World in Which IPv6 was a Good Design_](https://apenwarr.ca/log/20170810). I'm still proud of that article, bu...
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Two Workers Are Quadratically Better Than One
For latency, anyway. A common architecture pattern is the “task queue”: tasks enter an ordered queue, workers pop tasks and process them. This pattern is used everywhere from distributed systems to thread pools. It applies just as well to human systems, like waiting in line at a supermarket or a bank. Task queues are…
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SI Units for Request Rate
Request rate is the number of requests that arrive, or are serviced, or leave, during some period.
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Mini-ITX Seaberry Adds 11 PCIe Slots to a Raspberry Pi
Since the Compute Module 4 came along last year, there have been a few projects that use it that make me do a double-take: They did what with a Pi? Alftel's Seaberry is a carrier board for the CM4 in the Mini ITX form factor that adds on eleven PCI Express slots: 1 x16 slot (with x1 lane) in the standard ITX location…
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Spoiling Linux Kernel with "sanctioned" code
Last year I've fixed a bug in Linux kernel OHCI (USB 1.1) stack , which rendered my old printer unreliable: OHCI adds artificial delay of 1ms for each USB transfer of send-read pattern, while my very old, host-based printer expects very tight timings and constant latency, like some kind of CnC machine.
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Disk Utility still can't check and repair APFS volumes and containers (2021)
Don’t waste time trying to discover which files are still open when you want to check or repair an APFS disk and Disk Utility throws an error. Here’s the solution.
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Why Specifications Don't Compose
Recently my friend Lars Hupel and I had a discussion on why formal methods don’t compose well. You can read the conversation here. We focused mostly on composing formally-verified code. I want to talk a little more about the difficulties in composing specifications. This is half because it’s difficult for interesting…
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Multi-Core by Default
On multi-core programming, not as a special-case technique, but as a new dimension in all code.
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How does Sidekiq really work?
An investigation into the internals of Sidekiq, one of the most popular Ruby background job processors.
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Modernising RISC OS in 2020: is there hope for the ancient ARM OS?
The first computer I owned was a Sinclair ZX Spectrum, and I retain a lot of fondness for these tiny, cheap, severely-compromised machines. I just backed the ZX Spectrum Next kickstarter, for instance. But after I left university and got a job, I bought myself my first proper computer:…
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Recording and visualising the 20k system calls it takes to "import seaborn"
Last time we counted CPU instructions, let’s look at syscalls now!
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OpenBSD Router Guide
NOTE: Currently this guide only deals with IPv4 as most people still don't use IPv6 and many ISPs also still only use IPv4, but IPv6 is planned for a future update of the guide.
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Isolating Xwayland in a VM
In my last post, Qubes-lite with KVM and Wayland, I described setting up a Qubes-inspired Linux system that runs applications in virtual machines. A …
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Hidden Costs of Memory Allocation
It’s important to understand the cost of memory allocations, but this cost can be surprisingly tricky to measure. It seems reasonable to measure this cost by wrapping calls to new[] and delet…
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The Tower of Weakenings: Memory Models for Everyone
In my previous article I looked at the ways that Rust could be better at pointers. Half of the problems were fundamental issues that affect basically every programming language that lets you mess with pointers directly, and the other half were rust-specific issues. My article also proposed two solutions: for the…
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Compilers and IRs: LLVM IR, SPIR-V, and MLIR
Overall discussion on compilers and IRs (LLVM IR, SPIR-V, and MLIR): why they are in their current manner and how they would evolve
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Partitioning in Postgres, 2022 Edition
Tracking improvements to Postgres partitioning since 2017. In just five years it’s gone from a non-feature to a very good one.
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DOS Memory Management
The memory management in DOS is simple, but that simplicity may be deceptive. There are several rather interesting pitfalls that programming documentation often does not mention.
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Reading NFS at 25GB/s using FIO and libnfs
My current employer does a lot of really cool systems work that’s covered by NDAs. I recently did some work to integrate a cool open source tool into our workflow. Felt it deserved a blog post. NFS Testing Requires Parallelism. I work for Pure Storage. One of the products we make is a scale-out NFS1 (and…
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Understanding Glibc Malloc (2015)
I always got fascinated by heap memory. Questions such as How heap memory is obtained from kernel? How efficiently memory is managed? Is it managed by kernel or by library or by application itself?…
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